ARM: OMAP: Make FS USB omap1 only

As the FS USB code is not being actively used for omap2+
there's no point keeping it around for omap2+.

Let's make the FS USB platform init code omap1 only so
we can remove the last user of omap_read/write for omap2+,
and simplify things for further USB, DMA, and device tree
related work.

While at it, also group the mach includes for the related
drivers.

Cc: linux-usb@vger.kernel.org
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>